This invention relates to a device for taking liquid samples from a liquid circuit and is of the type which includes a needle head housing which is inserted in the circuit and through which the liquid flows. The housing includes arrangements for generating a pressure drop between a liquid inlet and a liquid outlet and there are further provided, at two locations of different operational pressure, hollow needles each having a terminal opening insertable into a sampling vessel.
Devices of the above-outlined type serve in particular for the taking of radioactive or toxic liquid samples which very frequently also include solid particles. Because of this circumstance the hollow needles and the immediately adjoining zones tend to be obstructed by such particles. In order to eliminate operational disturbances arising from such obstructions, reverse flow rinsing arrangements or filters may be provided. In case the device is associated with a reverse flow rinsing device, delays occur in the sample taking when the unclogging (rinsing) operation is performed and further, it is not always possible to eliminate the obstructions. Consequently, often the entire needle head has to be replaced. In case filters are used, the latter have to be frequently replaced because of clogging.